The official concept art from Ant-Man and the Wasp: Quantumania reveals that one character in Phase 5 was even more peculiar than portrayed in the film. The movie focused on the organisms within the Quantum Realm and introduced many bizarre elements. From the inhabitants and creatures to their customs and appearances, the MCU delved into a more peculiar side than ever before. This is demonstrated by concept art shared on Jerad Marantz's Instagram, who is part of Marvel Studios' visual development team. Marantz showcased his early designs for Veb, the rebellion fighter in the Quantum Realm played by David Dastmalchian.
Veb, the creature from the Quantum Realm, had an innovative weapon that harnessed his slime-like substance as ammunition. The gun would expel the slime, which would then return to Veb, causing him to change size as he "reloaded."
Will Any Quantum Realm Rebels Show Up Again In The MCU?
Following their escape from the Quantum Realm in Ant-Man and the Wasp: Quantumania, Scott, Hope, Cassie, Hank, and Janet's encounter with the Quantum Realm rebels leaves us wondering if we'll see them again in the MCU. While it may seem improbable, the door is always open for their return. The Quantum Realm fighters possess invaluable firsthand knowledge in confronting Kang the Conqueror and his formidable armies.
Given that Kang is set to be the main antagonist in the Multiverse Saga of the Marvel Cinematic Universe (MCU), it is possible that Scott will turn to his former allies from the Quantum Realm to counter Kang's return. The rebels from the Quantum Realm are already knowledgeable in dealing with Kang's followers, so Scott may seek their assistance in battling Kang during Avengers: The Kang Dynasty. However, this scenario is unlikely due to the unconventional tone of Ant-Man and the Wasp: Quantumania, as indicated by the original concept art for Veb's Phase 5 character.
Source: jsmarantz